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aircraft boy's

mountain man

mountain man

Active member
I was frog gigging sat and I fouled a plug strange I just replaced the plugs. my question what is the hottest plug I can run in a 220 gpu?

I just replaced my elec fuel pump and had that and the mec pump running at the same time maybe that is what fouled the plug?

I currently run autolite 386 spark plugs

any input would be great.
 
Hey Skeeter,
You think he might have a bad wire?
How about the gap?

Most I know swear that .018 is the best gap for a stock gpu.

I'd try the plugs Skeeter recommends.
If that don't do it, then I'd check that wire.

Just trying to help.
 
is the ngk a hotter plug?


this fuel pump issue should I be running the elec pump and the mech pump at the same time? or just use the elec for start up and let the mech take over on the run?
 
On gpu's we usually run NGK AB6 plugs, .018 gap on top and .015 if you have dual plugs. I haven't seen any problem with these fouling out unless the cylinder was wore out and burning alot of oil.

Larry
 
It can help a little. Does the plug that fouled look shiny black or a flat sooty black? Usually shiny tends to be oil fouled and sooty is fuel fouled.

Larry
 
Not trying to get off topic, but my 454 has started fouling plugs, someone told me to run a little cooler plug in it because it might be running rich. any suggestions?? The motor has about 450 hrs on it
 
Mountain Man
On the electric fuel pump issue, you can run it all the time with the mechanical.
Unless you have a really bad carb in need of a rebuilt that’s not causing the plugs to foul.
In a MD-3 (GPU) the electric and mechanical run together all the time and the operator has no control over it.
If that motor was in a lite plane, the electric fuel pump is used as a boost pump, for take offs and landings, I fly with mine turned off after take off. In my air boat I turn it off unless I get on it hard. I have just installed a fuel pressure gauge in the air boat, as soon as I get all the new wiring done and can get it fired, will let you know what it puts out on one then the other and both. I run Autolite 386 plugs in the boat gaped at a tight 17 gap.
Mags like a smaller gap, never a larger one, I have seen folks gap as little as 9 thousand, little closed for me, but it works.
Hope this helps, cant drive a air boat to well, but can fly the hell out of an air plane and repair them.

Bingo
A/P API. Retired
Long live Air America, With Gods Speed :shock:
 
I only use Champion Plugs. In all the years they have been the ones that we have found to work best for us. Are you running stock pistons? If so I would suggest a Champion D-18y. High Compression? then use a D-14. In stock compression Lycomings I like to use a Champion UD-16.
 
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